Scleral implants for treatment of presbyopia

Abstract

A method for treating presbyopia using a scleral insert is described. The scleral insert is prepared from either (or both) of two specific classes of polymeric materials having both viscous and elastic properties. The first class of polymeric materials has a glass transition temperature (T g ) at or below human body temperature (37° C.). The second class of polymeric materials has a melting temperature (T m ) at or below human body temperature (37° C.). The implant is stored in a frozen, rigid, elongated state prior to insertion in to the eye. Once it is placed on or within the sclera the insert responds to the increase in temperature, due to the surrounding physiochemical environment whereby it becomes soft and expands to reach its final shape. This implant can be inserted in to the eye through a much smaller incision than is used with conventional scleral implant techniques.

What is claimed is:  
     
         1 . A method of increasing the amplitude of accommodation of a human eye, having a crystalline lens and ciliary muscle by increasing the radial distance between the equator of the crystalline lens and the inner diameter of the ciliary muscle by inserting on or within the sclera a prosthetic implant made from a bio-compatible material which: 
 (i) is rigid at room temperature;    (ii) becomes elastic when warmed to a temperature above its melting temperature, T m ;    (iii) becomes rigid again when cooled to a temperature below its T m ; and    (iv) comprises a material selected from the group consisting of polymeric materials and mixtures of polymeric materials and waxes.    
     
     
         2 . A method of treating presbyopia in a human eye having a crystalline lens and ciliary muscle comprising increasing the effective working distance of the ciliary muscle by increasing the radial distance between the equator of the crystalline lens and the inner diameter of the ciliary muscle by inserting on or within the sclera a prosthetic implant made from a bio-compatible material which: 
 (i) is rigid at room temperature;    (ii) becomes elastic when warmed to a temperature above its melting temperature, T m ;    (iii) becomes rigid again when cooled to a temperature below its T m ; and    (iv) comprises a material selected from the group consisting of polymeric materials and mixtures of polymeric materials and waxes.    
     
     
         3 . The method according to  claim 2  wherein said scleral expansion is accomplished by inserting the said prosthetic implant into a channel beneath the sclera in the region of the ciliary body, said implant having a diameter greater than the interior diameter of the sclera in said region.  
     
     
         4 . The method according to  claim 2  wherein the scleral implant is processed according to the following steps: 
 a) prior to implantation, warming said implant to a temperature at which it becomes elastic;  
 b) forming said implant into dimensions suitable for insertion into a scleral channel;  
 c) allowing the implant to cool and resolidify in its stretched form;  
 d) inserting the stretched, rigid implant into said scleral channel; and  
 e) allowing said implant to warm to the body's temperature, thereby becoming elastic and conforming to the shape of the scleral channel.  
 
     
     
         5 . The method of  claim 4  wherein said implant conforms to the shape of the scleral channel in from about one second to about 120 seconds after it has been inserted.  
     
     
         6 . The method according to  claim 5  wherein said polymeric material is selected from the group consisting of polymers, homopolymers, cross-linked polymers and copolymers of acrylic esters, silicone elastomers, and combinations thereof.  
     
     
         7 . The method according to  claim 6  wherein said implant has a T m  of less than about 37° C.  
     
     
         8 . The method according to  claim 5  wherein said polymeric material is a side chain crystallizable polymer which comprises an acrylic ester of the formula:  
       
         
           
           
               
               
           
         
       
       wherein 
 X is H, or a C 1 -C 6  alkyl radical; and  
 R is a linear C 10 -C 26  alkyl radical.  
 
     
     
         9 . The method according to  claim 5  wherein said polymeric material is a main chain crystallizable polymer comprising the silicone elastomer stereo-regular poly[methyl (3,3,3-trifluoropropyl) siloxane].  
     
     
         10 . The method according to  claim 5  wherein said polymeric material in its stretched form is in the shape of a cylindrical rod-shaped implant which is tapered at one end to facilitate insertion into the scleral channel.  
     
     
         11 . The method according to  claim 10  wherein said implant has a length of from about 2 mm to about 8 mm and a diameter of from about 0.5 mm to about 3 mm after the shape recovery.  
     
     
         12 . The method according to  claim 10  wherein said implant in its stretched form has a length of from about 8 mm to about 35 mm and a diameter of from about 0.3 mm to about 2 mm.  
     
     
         13 . The method according to  claim 12  wherein said polymeric material comprises poly(stearyl methacrylate).  
     
     
         14 . A method for increasing the amplitude of accommodation of a human eye having a crystalline lens and ciliary muscle comprising increasing the effective working distance of the ciliary muscle by increasing the radial distance between the equator of the crystalline lens and the inner diameter of the ciliary muscle by inserting on or within the sclera a prosthetic implant made from a bio-compatible material which: 
 (i) is rigid at room temperature;    (ii) becomes elastic when warmed to a temperature above its glass transition temperature, T g ;    (iii) becomes rigid again when cooled to a temperature below its T g ; and    (iv) comprises a material selected from the group consisting of polymeric materials and mixtures of polymeric materials and waxes.    
     
     
         15 . A method of treating presbyopia in a human eye having a crystalline lens and ciliary muscle comprising increasing the effective working distance of the ciliary muscle by increasing the radial distance between the equator of the crystalline lens and the inner diameter of the ciliary muscle by inserting on or within the sclera prosthetic implant made from a bio-compatible material which: 
 (i) is rigid at room temperature;    (ii) becomes elastic when warmed to a temperature above its glass transition temperature, T g ;    (iii) becomes rigid again when cooled to a temperature below its T g ; and    (iv) comprises a material selected from the group consisting of polymeric materials and mixtures of polymeric materials and waxes.    
     
     
         16 . The method according to  claim 15  wherein the said scleral expansion is accomplished by inserting into a channel beneath the sclera in the region of the ciliary body said prosthetic implant having a diameter greater than the interior diameter of the sclera in said region.  
     
     
         17 . The method according to  claim 16  wherein prosthetic implant is processed according to the following steps: 
 a) prior to insertion, warming said implant to a temperature at which it becomes elastic;  
 b) forming said implant into dimensions suitable for insertion into a scleral channel;  
 c) allowing said composition to cool and re-solidify in its de-formed state;  
 d) inserting said stretched, rigid implant into said scleral channel; and  
 e) allowing said implant to warm to the body's temperature thereby becoming elastic and conforming to the shape of the scleral channel.  
 
     
     
         18 . The method according to  claim 17  wherein the implant fills and includes the scleral channel in about one minute to about seven minutes after it has been inserted.  
     
     
         19 . The method according to  claim 18  wherein said polymeric material is selected from the group consisting of polymers, homopolymers, cross-linked polymers and copolymers of silicones, acrylic esters, polyurethanes, hydrocarbon polymers and combinations thereof.  
     
     
         20 . The method according to  claim 17  wherein said implant has a T g  of less than about 37° C.  
     
     
         21 . The method according to  claim 17  wherein said polymeric material is an acrylic ester.  
     
     
         22 . The method according to  claim 17  wherein said polymeric material in its stretched form is in the shape of a cylindrical rod-shaped implant which is tapered at one end to facilitate insertion into the scleral channel.  
     
     
         23 . The method according to  claim 17  wherein said implant has a length of from about 2 mm to about 8 mm and a diameter of from about 0.5 mm to about 3 μm after shape recovery.  
     
     
         24 . The method according to  claim 17  wherein said implant in its stretched form has a length of from about 8 mm to about 35 mm and a diameter of from about 0.3 mm to about 2 mm.  
     
     
         25 . The method according to  claim 17  wherein said implant is comprised of a polymer of polymethylmethacrylate and polylaurylmethacrylate.